1. Field of the invention
This invention relates to a sealing structure for a panel-mounted electrical connector fitted in a mounting hole formed in a panel.
2. Description of the prior art
FIGS. 7 to 9 illustrate a conventional sealing structure for providing waterproofing between a mounting hole 136 formed in a panel 135 and a panel-mounted electrical connector 130 fitted in the mounting hole 136. The panel-mounted connector 130 having the shown sealing structure comprises a fixed connector housing 131 with a hood 132 and a detachable connector housing 133 fitted in the hood 132. In the mounting of the fixed connector housing 131, the hood 132 of the fixed connector housing 131 is fitted into the mounting hole 136 from the inside of the panel 135 or from the left-hand side as viewed in FIG. 7. A locking piece 134 is then engaged with the edge of the mounting hole 136. 0n the other hand, the detachable connector housing 133 is fitted into the hood 132 from the outside of the panel 135 or from the right-hand side as viewed in FIG. 7. The detachable connector housing 133 is then fixed by a bolt 138 with a grommet 137 covering an opening of the hood 132.
A seal 140 is integrally formed along the outer periphery of the grommet 137 and is disposed annularly along the peripheral edge of the mounting hole 136. The seal 140 has an angular section so as to be pointed toward the panel 135, as shown in FIG. 8. The seal 140 is pressed against an outside seal face 139 of the panel 135 upon attachment of the detachable connector housing 133 to the fixed connector housing 131, whereupon the seal 140 is closely adhered to the seal face 139 with elastic deformation. Thus, since the whole peripheral edge of the mounting hole 136 is surrounded by the seal 140, the outer periphery of the detachable connector housing 133 is isolated from the seal face 139. Consequently, water or the like can be prevented from invading the inside of the panel 135 from the outside thereof through a gap between the mounting hole 136 and the panel-mounted connector 130.
The above-described sealing structure has the following problems. When the seal 140 is closely adhered to the panel 135, the pointed distal end of the seal 140 first undergoes the elastic deformation, and finally the whole seal elastically deforms. Since the seal 140 has the angular section, the elastic deformation thereof is unstable. Accordingly, there is a possibility that the elastic deformation of the seal 140 is not uniform throughout an annular path along which the seal 140 is closely adhered to the panel 135 so as to surround the mounting hole 136. More specifically, the angular distal end of the seal 140 deviates in one part of the path toward the outer peripheral side while as the result of the elastic deformation it deviates in another part of the path toward the inner peripheral side. Consequently, the seal 140 is twisted into a corrugated form in a portion thereof where it is repeatedly deviated alternately to inner and outer peripheral sides. Waterproofing is reduced in that portion of the seal 140.
Furthermore, the seal 140 cannot seal a gap Sa between the peripheral edge of the mounting hole 136 and the hood 132 of the fixed connector housing 131 and a gap Sb between the hood 132 and the detachable connector housing, as shown in FIG. 8. Accordingly, water cannot be prevented from passing through these gaps. For example, water drops due to dew condensation on the inner face of the panel 135, or the left-hand face thereof as viewed in FIGS. 7-9, fall and invade the interior of each connector housing through the gaps Sa and Sb.